Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Taxes And Tax Related [Line Items]
Effective tax rate			1.50%	9.30%
Income tax expense	$ 4	$ 469	$ 298	$ 650
Deferred tax asset related to excess tax benefits from stock compensation	$ 2,600		$ 2,567
Minimum [Member] | Federal Tax Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination			2010
Minimum [Member] | State and Local Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination			2008
Maximum [Member] | Federal Tax Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination			2013
Maximum [Member] | State and Local Jurisdiction [Member]
Income Taxes And Tax Related [Line Items]
Years subject to income tax examination			2013